A variety of mechanisms have been employed for joining and securing the free ends of watch bands and bracelets. One form of metal clasp that is in wide-spread use for joining and securing the ends of flexible metal mesh watch bands comprises a first element in the form of a U-shaped frame member adapted to receive a section of one of the bands and which includes a clamping mechanism to releasably secure the frame member at a predetermined position on a section of the band. A second joining member is permanently secured to the terminus of the free end of the second band. In order to permit the wearer to initially join the free ends, a combination of a transverse bar or pin and a hook member are respectively provided on the free ends of the band. The initial hook and bar connection allows the wearer to determine that the fit is appropriate, and this initial joining step can be facilitated by use of a pivoting locking plate. After the hook has been placed over the bar, the pivoting locking plate is rotated to secure the locking mechanism. Representative structures for this type of metal locking clasp are shown in U.S. Pat. Nos. 4,359,808; 3,425,104 and others.
Although generally reliable, the locking clasps of the prior art have only a single locking mechanism and that mechanism can be unintentionally released when the pivoting locking plate is accidently opened. Once the locking plate is lifted, the hook is easily displaced from the bar and the free ends separate. It would therefore be desirable to provide a locking clasp having a second or safety lock that would prevent the accidental inadvertent opening of the first or primary lock.
It is therefore an object of this invention to provide an improved metal clasp for joining the free ends of watch bands, bracelets and the like which has a double-locking mechanism to provide protection against the inadvertent unlocking of the clasp and the potential loss or damage to the watch.
It is another object of the invention to provide a double-locking metal safety clasp which is compact and aesthetically attractive, and which at the same time, is relatively simple in its mode of operation, as well as in its construction, and which is therefore economical to manufacture.
It is yet another object of this invention to provide a double-locking metal safety clasp in which a second locking mechanism can be adapted for use with single lock clasps with a minimum of retooling for their manufacture.